I used longer stainless bolts to mount the U-cradle bracket to the ford racing light bar. Then I put a blob of JB weld on the tip of the bolts so you cant back off the nuts holding the U-cradle to light bar. If i need to take the U-Cradle off I have enough room to cut the bolt above the blob of JB weld and unscrew the nut.
That JB weld idea might be just the trick for my lights. I think I'll give that a go. Have you tried to break it loose with a wrench at all? Just curious if it'll hold up if a thief tries to have a go at it.